Mix cake according to manufacturer’s instructions. Place paper liners into a conventional cupcake pan. Use a #2 blue scoop to deposit 1.5 oz batter into each cavity. Bake at 350°F until cupcakes spring back lightly when touched. Let cool completely. Using a small round cutter, remove the center of each cupcake, pipe in peach filling. Mix together 3 pounds of buttercreme and 1 Tbsp of bourbon flavoring. Ice cupcakes with prepared buttercream and decorate with fresh peach slices.